1. Field of the Invention
The present invention relates to a method of manufacturing a plasma display panel, which is known as a display device.
2. Description of the Related Art
A plasma display panel (hereinafter abbreviated as “PDP”) is a display device having excellent visibility and featuring a large screen, flatness and light weight. The systems of discharging a PDP include an alternating-current (AC) type and direct-current (DC) type. The electrode structures thereof include a three-electrode surface-discharge type and an opposite-discharge type. Now, the current mainstream is an AC surface-discharge type PDP, because this type of PDP is suitable for higher definition and easy to manufacture.
Generally, an AC surface-discharge type PDP has a large number of discharge cells formed between a front panel and a rear panel faced with each other. In the front panel, a plurality of display electrodes, each made of a pair of scan electrode and sustain electrode, are formed on a front glass substrate in parallel with each other. A dielectric layer and a protective layer are formed to cover these display electrodes. In the rear panel, a plurality of parallel address electrodes is formed on a rear glass substrate. A dielectric layer is formed on the address electrodes to cover them. Further, a plurality of barrier ribs is formed on the dielectric layer in parallel with the address electrodes. Phosphor layers are formed on the surface of the dielectric layer and the side faces of the barrier ribs. Then, the front panel and the rear panel are faced with each other and hermetically joined, i.e. sealed, together so that the display electrodes and data electrodes are orthogonal to each other. Thereafter, a discharge gas is filled into a discharge space formed therebetween to form a PDP.
For a PDP fabricated as above, a voltage necessary for uniformly lighting the entire panel (hereinafter simply referred to as “operating voltage”) is high, and discharge itself is unstable. These are because impure gases, such as H2O, CO2, and hydrocarbon gas, are adsorbed onto the surface of the protective layer formed of MgO. To solve this problem, a method of manufacturing a PDP includes an aging step in which sputtering caused by aging discharge removes these adsorbed gases. This step decreases the operating voltage and makes discharge characteristics uniform and stable.
As such, a method of aging including pulse voltage of rectangular waves in opposite phases has conventionally been applied across scan electrodes and sustain electrodes for a long period of time as alternating voltage. However, to shorten the aging time, another method is proposed (see Japanese Patent Unexamined Publication No. 2002-231141, for example). In this method, pulse voltage of rectangular waves in opposite phases is applied across display electrodes, and pulse voltage having a waveform in the same phase as the voltage waveform applied to sustain electrodes is also applied to address electrodes to cause discharge between the scan electrodes and sustain electrodes, and between the scan electrodes and the address electrodes.
However, even with this aging method, it takes approximately 10 hours until aging is completed, i.e. the operating voltage is decreased and discharge is stabilized. Such aging for a long period of time is one of the factors in huge power consumption and increases costs of manufacturing PDPs, the area of a factory site, and the facilities for maintaining the environment of the factory, such as air-conditioning equipment. It is also obvious that these problems become more serious as PDPs will have a larger screen and the amount of their production will increase in the future.
The present invention addresses these problems, and aims to achieve a method of manufacturing a PDP capable of reducing aging time and performing more power-efficient aging.